Catheters have long been used for the treatment of diseases of the cardiovascular system, such as treatment or removal of stenosis. For example, in a percutaneous transluminal coronary angioplasty (PTCA) procedure, a catheter is used to insert a balloon into a patient's cardiovascular system, position the balloon at a narrowed treatment location, inflate the balloon to expand the narrowing, and remove the balloon from the patient. Another example is the placement of a prosthetic stent in the body on a permanent or semi-permanent basis to support weakened or diseased vascular walls to avoid closure or rupture thereof.
These non-surgical interventional procedures often avoid the necessity of major surgical operations. However, one common problem associated with these procedures is the potential release into the bloodstream of atherosclerotic or thrombotic debris that can embolize distal vasculature and cause significant health problems to the patient. For example, during deployment of a stent, it is possible for the metal struts of the stent to cut into the stenosis and shear off pieces of plaque which become embolic debris that can travel downstream and lodge somewhere in the patient's vascular system. Further, particles of clot or plaque material can sometimes dislodge from the stenosis during a balloon angioplasty procedure and become released into the bloodstream.
Medical devices have been developed to attempt to deal with the problem created when debris or fragments enter the circulatory system during vessel treatment. Practitioners have approached prevention of escaped emboli through use of occlusion devices, filters, lysing, and aspiration techniques. For example, it is known to remove the embolic material by capturing emboli in a filter positioned distal of the treatment area.
Alternatively, an occlusion device may be deployed distally or proximally of the treatment area to block the flow of contaminated blood, which can then be aspirated along with the embolic debris contained therein. Known occlusion guidewires include an occluder membrane surrounding an expandable mechanical structure that is actuatable by push-pull action of a core wire through an outer tubular member. However, such expandable mechanical structure can be complex to fabricate and can add undesirably to the overall collapsed profile of the occlusion guidewire.
Other known occlusion catheters or guidewires include an inflatable occlusion balloon located adjacent the distal end of a hollow guidewire. Dilute radiopaque contrast agent is forced through an inflation lumen to inflate and deflate the occlusion balloon. However, operating the balloon may take longer than desired due to the viscosity of the inflation medium, the small size of the inflation lumen, and the requirement to attach, detach and operate one or more inflation accessories at the proximal end of the catheter or guidewire. Accordingly, there is a need for a simplified, low-profile embolic protection device.